A polysaccharide-based hydrogel adsorbent, its preparation method and application

Abstract

The application belongs to the technical field of printing and dyeing wastewater treatment, and particularly relates to a polysaccharide-based hydrogel adsorbent as well as a preparation method and application thereof. The application provides a polysaccharide-based hydrogel adsorbent, which is prepared from sodium carboxymethyl starch, sodium carboxymethyl cellulose, acrylamide, polyvinyl alcohol and itaconic acid as raw materials, and is obtained through grafting reaction and crosslinking reaction to obtain a preliminary reaction product; and the preliminary reaction product is repeatedly frozen and thawed to obtain the target adsorbent. It is verified through experiments that the adsorbent has good mechanical properties and adsorption performance, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of dyeing and printing wastewater treatment technology, specifically relating to a polysaccharide-based hydrogel adsorbent, its preparation method, and its application. Background Technology

[0002] With the development of the dyeing and printing industry, large amounts of organic dyes and heavy metal ions are discharged into water bodies. Statistics show that wastewater from the dyeing and printing industry accounts for one-third of the total discharge of dye and heavy metal ion wastewater, while the average wastewater reuse rate is only about 7%. The large-scale discharge of wastewater containing dyes and heavy metal ions leads to serious environmental pollution, and wastewater treatment has attracted widespread attention.

[0003] Currently, wastewater treatment methods include electrolysis, flocculation and sedimentation, photocatalytic oxidation, biological methods, and adsorption. Among these, adsorption offers advantages such as low cost, ease of operation, non-toxicity, and the reusability of adsorbent materials. Natural adsorbent materials have become a research and application hotspot in the wastewater treatment industry due to their low cost and biodegradability. Polysaccharides are a class of abundant, non-toxic natural water treatment materials; however, their application in wastewater treatment is limited by their small adsorption capacity and low selectivity when used directly as adsorbents. Therefore, to achieve the desired adsorption function, it is necessary to introduce active functional groups onto the polysaccharide surface for functional modification.

[0004] Hydrogels possess a three-dimensional network structure and hydrophilic groups. These three-dimensional structures contain many hydrophilic groups such as -OH, -SO3H, -CONH2, and -COOH, which can chelate with dyes and heavy metal ions, thereby effectively removing them. Preparing hydrogels from natural polysaccharides can reduce production costs, decrease toxicity, and improve biodegradability and reusability. However, polysaccharide-based hydrogels have inherent structural defects such as weak intramolecular interactions, insufficient cross-linking, and weak interchain forces. In flow systems, factors like water scouring and shear forces can cause these issues. If the elastic modulus of the hydrogel is too low, it is prone to deformation, breakage, or even loss, leading not only to adsorbent loss but also to bed blockage and secondary pollution. For example, CN 105903442 A discloses a polysaccharide-based hydrogel for wastewater treatment. Although it has some methylene blue adsorption capacity, its mechanical properties are weak, its structure is loose, and its stability is poor.

[0005] Given the above background, there is an urgent need to develop a polysaccharide-based hydrogel with good adsorption effect and mechanical properties. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a polysaccharide-based hydrogel adsorbent with good mechanical and adsorption properties, its preparation method and application.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] Technical Topic 1

[0009] A method for preparing a polysaccharide-based hydrogel adsorbent, the key of which includes the following steps:

[0010] S1: Preparation of materials

[0011] I. Disperse sodium carboxymethyl starch and polyvinyl alcohol in water, heat to boiling, and obtain solution A;

[0012] II. Dissolve sodium carboxymethyl cellulose in water to obtain solution B.

[0013] III. Add water to itaconic acid and then add an alkaline solution to dissolve itaconic acid, and control the neutralization degree of itaconic acid to 80~100%. Then dissolve a certain amount of acrylamide and N,N′-methylenebisacrylamide in the resulting mixture, and denote it as solution C.

[0014] IV. Dissolve ammonium persulfate in water to obtain solution D;

[0015] S2: Initial reaction

[0016] Mix solutions A, B, and C thoroughly, then add solution D and mix thoroughly. Place the reaction system under a protective gas and react at a constant temperature of 60-80℃ for 3-5 hours to obtain the preliminary reaction product.

[0017] S3: Freeze-thaw

[0018] The preliminary reaction product obtained from S2 was repeatedly freeze-thawed to obtain a polysaccharide-based hydrogel adsorbent.

[0019] As a further improvement of the present invention, the alkaline solution is an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide.

[0020] As a further improvement of the present invention, the dosage relationship of sodium carboxymethyl starch, polyvinyl alcohol, sodium carboxymethyl cellulose, itaconic acid, and ammonium persulfate in S1 is 1g: 0.3~0.7g: 0.3~0.5g: 0.5~1.5g: 0.06~0.08g.

[0021] As a further improvement of the present invention, the dosage relationship of sodium carboxymethyl starch, polyvinyl alcohol, sodium carboxymethyl cellulose, itaconic acid, and ammonium persulfate in S1 is 1g:0.5g:0.5g:1g:0.06g.

[0022] As a further improvement of the present invention, in step III of S1, the dosage relationship of itaconic acid, acrylamide and N,N′-methylenebisacrylamide is 0.5~1.5g: 2~4g: 0.3~0.5g.

[0023] As a further improvement of the present invention, in step III of S1, the dosage relationship of itaconic acid, acrylamide and N,N′-methylenebisacrylamide is 1g:3g:0.4g.

[0024] As a further improvement of the present invention, the conditions for repeated freeze-thaw cycles in S3 are: freezing at -25 to -35°C for 8 to 12 hours, then placing at room temperature for 8 to 10 hours, and repeating 3 to 4 times.

[0025] As a further improvement of the present invention, the protective gas is one of nitrogen, helium, and argon.

[0026] As a further improvement of the present invention, the heating and boiling time in S1 is 3~10 min.

[0027] As a further improvement of the present invention, the ratio of 1.0g sodium carboxymethyl starch to water in S101 is 1g: 20~40mL;

[0028] As a further improvement of the present invention, the ratio of sodium carboxymethyl cellulose to water in S102 is 0.5g: 20~40mL;

[0029] As a further improvement of the present invention, the ratio of itaconic acid to water in S103 is 1g: 5~15mL;

[0030] As a further improvement of the present invention, the ratio of 0.06g of ammonium persulfate to water in S104 is 0.06g: 5~10mL.

[0031] Technical Theme Two

[0032] A polysaccharide-based hydrogel adsorbent prepared by the preparation method described in Technical Subject 1.

[0033] Technical Theme 3

[0034] Application of polysaccharide-based hydrogel adsorbents in the field of organic dye adsorption, as described in Technical Topic 2.

[0035] As a further improvement of the present invention, the adsorbent is used to adsorb methylene blue in wastewater.

[0036] The beneficial effects of adopting the above technical solution are as follows:

[0037] This invention constructs a hydrogel that combines mechanical and adsorption properties by selecting appropriate raw materials, crosslinking agents, and preparation conditions.

[0038] The hydrogel preparation method provided by this invention is simple, the raw materials are readily available, and experimental verification shows that it has a good methylene blue adsorption effect. Attached Figure Description

[0039] Figure 1 These are morphological photographs of the polysaccharide-based hydrogel adsorbent prepared in Example 1 of this invention.

[0040] Figure 2 This is the infrared spectrum of the polysaccharide-based hydrogel adsorbent prepared in Example 1 of this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described clearly and completely below in conjunction with specific embodiments.

[0042] Sodium carboxymethyl cellulose used in this application was purchased from Tianjin Damao Chemical Reagent Partnership, CAS No. 9004-32-4;

[0043] Sodium carboxymethyl starch was purchased from Aladdin, item number C105665, CAS number 9063-38-1;

[0044] Polyvinyl alcohol was purchased from Shanghai Chenqi Chemical Technology Co., Ltd., model number 1792.

[0045] Example 1

[0046] S1: Preparation of materials

[0047] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0048] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0049] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0050] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0051] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4# Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0052] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0053] Infrared detection was performed on the hydrogel obtained in Example 1, and the results are as follows: Figure 2 As shown, at 3340 and 3190cm -1 The peak is a double peak for primary amines; 1601 cm⁻¹ -1 The absorption peak at 1652 cm⁻¹ corresponds to the C=O group in the amide group. Due to the influence of intramolecular hydrogen bonding, the absorption peak shifts towards lower wavenumbers; 1652 and 1447 cm⁻¹ -1 -COO - Absorption peaks for asymmetric and symmetric stretching vibrations; 1394 cm⁻¹ -1 The absorption peak at this point is the bending vibration of NH; 10¹⁸ cm⁻¹ -1 The peaks at this point represent the vibrational peaks of CO in the polysaccharide ring. The presence of these peaks indicates the existence of polysaccharide chains, amide groups, carboxyl groups, and intramolecular hydrogen bonds within the hydrogel structure, proving the successful synthesis of the target product.

[0054] Example 2

[0055] S1: Preparation of materials

[0056] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.3g of polyvinyl alcohol and place them in 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0057] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0058] S103. Weigh 1.5g of itaconic acid and place it in 3... # Add 10 mL of deionized water to the beaker, then add 15 wt% sodium hydroxide solution dropwise until itaconic acid dissolves and is neutralized to 80%. Next, add 4.0 g of acrylamide and 0.5 g of N,N-methylenebisacrylamide to the solution, stir to dissolve, and set aside for later use.

[0059] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0060] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0061] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0062] Example 3

[0063] S1: Preparation of materials

[0064] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.7g of polyvinyl alcohol and place them in 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0065] S102. Weigh 0.3g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0066] S103. Weigh 0.5g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add sodium hydroxide solution (15 wt%) dropwise until itaconic acid dissolves and is neutralized to 80%. Next, add 2.0 g of acrylamide and 0.3 g of N,N-methylenebisacrylamide to the solution, stir to dissolve, and set aside for later use.

[0067] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0068] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0069] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0070] Example 4

[0071] S1: Preparation of materials

[0072] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 3 minutes. Set aside for use.

[0073] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0074] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to a beaker, then add 15 wt% sodium hydroxide solution dropwise until itaconic acid dissolves and is 100% neutralized. Next, add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve, and set aside for later use.

[0075] S104. Weigh 0.08 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0076] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, purge the air in the beaker with nitrogen gas, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for a constant temperature reaction for 3 hours to obtain the preliminary reaction product.

[0077] S3: Freeze the gel at -25°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 4 times to obtain the polysaccharide-based hydrogel adsorbent.

[0078] Example 5

[0079] S1: Preparation of materials

[0080] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 10 minutes. Set aside for use.

[0081] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0082] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0083] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0084] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, purge the air in the beaker with nitrogen gas, then seal the mouth of the beaker with plastic wrap, and place it in an 80℃ water bath for a constant temperature reaction for 3 hours to obtain the preliminary reaction product.

[0085] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0086] Example 6

[0087] S1: Preparation of materials

[0088] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0089] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0090] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0091] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0092] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, purge the air in the beaker with nitrogen gas, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for a constant temperature reaction for 5 hours to obtain the preliminary reaction product.

[0093] S3: Freeze the gel at -35°C for 12 hours, then remove it and thaw it at room temperature for 10 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0094] Example 7

[0095] S1: Preparation of materials

[0096] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0097] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0098] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0099] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0100] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0101] S3: Freeze the gel at -30°C for 8 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0102] Comparative Example 1

[0103] S1: Preparation of materials

[0104] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0105] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0106] S103. Weigh 2.0g of itaconic acid and put it into 3 # Add 10 mL of deionized water to a beaker, then add dropwise sodium hydroxide solution (15 wt%) until itaconic acid dissolves and is neutralized to 80%. Next, add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve, and set aside for later use.

[0107] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0108] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0109] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0110] Comparative Example 2

[0111] S1: Preparation of materials

[0112] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0113] S102. Weigh 0.5g of sodium carboxymethyl starch and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0114] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0115] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0116] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0117] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0118] Comparative Example 3

[0119] The preparation method is the same as in Example 1, except that the amount of sodium carboxymethyl starch added is 0.5g and the amount of sodium carboxymethyl cellulose added is 1.0g, and the resulting product does not form a gel.

[0120] Comparative Example 4

[0121] S1: Preparation of materials

[0122] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0123] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0124] S103. Weigh 1.0g of itaconic acid and place it in 3 #Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 5.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0125] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0126] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0127] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0128] Comparative Example 5

[0129] S1: Preparation of materials

[0130] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0131] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0132] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0133] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then transfer 3 μL of tetramethylethylenediamine into the weighing boat, and dissolve it in 5 mL of deionized water for later use, yielding 4 g of ammonium persulfate. # Solution;

[0134] S2: 1 # 2# 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0135] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0136] Comparative Example 6

[0137] S1: Preparation of materials

[0138] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0139] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0140] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0141] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0142] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0143] S3: Freeze the gel in a -30°C freezer for 12 hours, then remove it and dissolve it at room temperature for 8 hours to obtain the polysaccharide-based hydrogel adsorbent.

[0144] Comparative Example 7

[0145] S1: Preparation of materials

[0146] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of sodium carboxymethyl starch and 0.5g of polyethylene glycol and place them in 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0147] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0148] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0149] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0150] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0151] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0152] Comparative Example 8

[0153] The preparation method is the same as in Example 1, except that N,N-methylenebisacrylamide is replaced with an equal mass of polyethylene glycol diacrylate or epichlorohydrin, and the resulting product does not form a gel.

[0154] Comparative Example 9

[0155] S1: Preparation of materials

[0156] S101. Take 3 beakers and label them 1-3. # Weigh 1.0g of sodium carboxymethyl starch and put it into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0157] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0158] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0159] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0160] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0161] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0162] Comparative Example 10

[0163] S1: Preparation of materials

[0164] S101. Take 3 beakers and label them 1-3. # Weigh out 1.0g of corn starch and 0.5g of polyvinyl alcohol and put them into 1 # Place 30 mL of deionized water in a beaker and heat to a boil for 5 minutes. Set aside for use.

[0165] S102. Weigh 0.5g of sodium carboxymethyl cellulose and place it in 2 # Dissolve the contents in 30 mL of deionized water in a beaker and set aside for later use.

[0166] S103. Weigh 1.0g of itaconic acid and place it in 3 # Add 10 mL of deionized water to the beaker, then add 3.28 g of sodium hydroxide solution (15 wt%) dropwise. The itaconic acid will dissolve and the degree of neutralization will be 80%. Then add 3.0 g of acrylamide and 0.4 g of N,N-methylenebisacrylamide to the solution, stir to dissolve and set aside for later use.

[0167] S104. Weigh 0.06 g of ammonium persulfate using a weighing boat, then dissolve it in 5 mL of deionized water in the weighing boat for later use, yielding 4 g of ammonium persulfate. # Solution;

[0168] S2: 1 # 2 # 3 # Mix the solutions thoroughly and stir well, then add 4 # Pour the solution into the mixed solution, stir well, introduce nitrogen gas into the beaker to remove the air in the beaker, then seal the mouth of the beaker with plastic wrap, and place it in a 60℃ water bath for constant temperature reaction for 4 hours to obtain the preliminary reaction product.

[0169] S3: Freeze the gel at -30°C for 12 hours, then remove it and let it thaw at room temperature for 8 hours. Repeat this freeze-thaw cycle 3 times to obtain the polysaccharide-based hydrogel adsorbent.

[0170] Example 1

[0171] This example examines the adsorption effect of the hydrogel provided by the present invention on methylene blue:

[0172] A 100 mg / L methylene blue aqueous solution was prepared without adjusting the pH value. The polysaccharide-based hydrogel adsorbents prepared in Examples 1-6, Comparative Examples 1-2, Comparative Examples 4-7, and Comparative Examples 9-10 of this invention were added at a dosage of 100 mg / L. The adsorption temperature was controlled at 25°C and the adsorption time was 5 h. The adsorption effect of the hydrogel is shown in Table 1.

[0173] Example 2

[0174] The hydrogel described in this application was cut into 1cm×1cm×1cm cubes, and the compressive modulus of the hydrogel (1cm×1cm×1cm) was tested using a universal testing machine at a compression rate of 10mm / min and a constant strain of 50%. The compressive modulus of the obtained materials is shown in Table 1.

[0175] Table 1

[0176]

[0177] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polysaccharide-based hydrogel adsorbent, characterized in that, Includes the following steps: S1: Preparation of materials I. Disperse sodium carboxymethyl starch and polyvinyl alcohol in water, heat to boiling, and obtain solution A; II. Dissolve sodium carboxymethyl cellulose in water to obtain solution B. III. Add water to itaconic acid and then add an alkaline solution to dissolve itaconic acid, and control the neutralization degree of itaconic acid to 80~100%. Then dissolve a certain amount of acrylamide and N,N′-methylenebisacrylamide in the resulting mixture, and denote it as solution C. IV. Dissolve ammonium persulfate in water to obtain solution D; S2: Initial reaction Mix solutions A, B, and C thoroughly, then add solution D and mix thoroughly. Place the reaction system under a protective gas and react at a constant temperature of 60-80℃ for 3-5 hours to obtain the preliminary reaction product. S3: Freeze-thaw The preliminary reaction product obtained from S2 was repeatedly freeze-thawed to obtain a polysaccharide-based hydrogel adsorbent; The dosage relationship of sodium carboxymethyl starch, polyvinyl alcohol, sodium carboxymethyl cellulose, itaconic acid, and ammonium persulfate in S1 is 1g: 0.3~0.7g: 0.3~0.5g: 0.5~1.5g: 0.06~0.08g; In step III of S1, the dosage relationship of itaconic acid, acrylamide and N,N′-methylenebisacrylamide is 0.5~1.5g: 2~4g: 0.3~0.5g; The conditions for repeated freeze-thaw cycles in S3 are: freezing at -25 to -35°C for 8 to 12 hours, then leaving at room temperature for 8 to 10 hours, and repeating this process 3 to 4 times.

2. The method for preparing a polysaccharide-based hydrogel adsorbent according to claim 1, characterized in that, The dosage relationship of sodium carboxymethyl starch, polyvinyl alcohol, sodium carboxymethyl cellulose, itaconic acid, and ammonium persulfate in S1 is 1g:0.5g:0.5g:1g:0.06g.

3. The method for preparing a polysaccharide-based hydrogel adsorbent according to claim 1, characterized in that, In step III of S1, the dosage relationship of itaconic acid, acrylamide and N,N′-methylenebisacrylamide is 1g:3g:0.4g.

4. The method for preparing a polysaccharide-based hydrogel adsorbent according to claim 1, characterized in that, The protective gas is one of nitrogen, helium, or argon.

5. A polysaccharide-based hydrogel adsorbent prepared by the preparation method according to any one of claims 1-4.

6. The application of the polysaccharide-based hydrogel adsorbent as described in claim 5 in the field of organic dye adsorption.

7. The application according to claim 6, characterized in that... The adsorbent is used to adsorb methylene blue into wastewater.

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